Nepal flash floods: Why ongoing relief operations are a battle against time and ravaged terrain

With at least 547 people killed in Nepal after flash floods that ravaged the country just days ago, destroying life and infrastructure on a large scale, rescue operations in the country are taking place on a war footing, even as the number of those who have gone missing nears the 2,000-mark.

320 of these are Indians, who are either missing or have gone incommunicado, amid rescue operations on a war footing in the country, which have so far saved hundreds of people.

This comes after a sudden, massive surge of mud and rock entered the Bhote Koshi and Trishuli rivers from the Tibetan side, triggering terrible floods that continue to move downstream, which put Indian states like Bihar and Uttar Pradesh on high alert.

A number of bodies, thought to have died as a result of the flash floods in Nepal, also flowed downstream into India, though they have yet to be identified.

Local authorities first explained that it had been a Glacial Lake Outburst Flood (GLOF), or a large-scale ice avalanche—and not localised rain—that allegedly dammed a river in Tibet’s Kerung area temporarily, which sparked the flash floods.

However, satellite images later revealed that the real cause of the flash floods in Nepal was not only the collapse of a glacier, but also a “big bedrock failure that took part of the glacier with it", as per an Associated Press report, citing Kristen Cook and Dan Shugar.

These bedrock fragments combined with water and mud to create destructive brown sediment-filled waves that raged downstream, widening the Bhote Koshi and Trishuli rivers and causing major destruction.

Aid efforts

Rescue and relief operations in flood-hit Nepal have been intermittent at times due to factors like the nature of the terrain, evolving weather and geological constraints, and the widespread collapse of critical infrastructure, such as roads, bridges, and cellular networks.

The Prithvi Highway, which has remained closed since the floods hit the country on Wednesday, is one such example, which has severely impacted the movement of food and fuel to the Kathmandu Valley.

Efforts are on to repair the 180km stretch from Bharatpur to Nagdhunga, the main entry point to the Kathmandu Valley, in addition to at least 19 bridges and large stretches of roads that were washed away by the powerful floodwaters.

Nepal had earlier declined offers from several countries—including India and China—to send specialised teams to aid search and rescue efforts, as it had faced issues when a 2015 earthquake led to an influx of foreign search and rescue teams, as per a Kathmandu Post report.

However, the country continued to receive relief supplies from various countries, including India, which sent its third 10-tonne tranche of Humanitarian Assistance and Disaster Relief (HADR).

"The assistance includes portable generator sets, dignity kits, food packets and water purification tablets," wrote External Affairs Minister S. Jaishankar in an X post on Friday, announcing the move.

India also dispatched an 11-member team of doctors and paramedics, in addition to a reconnaissance team to aid tunnel rescue operations.

Jaishankar added that India has also offered Bailey bridges, which are portable, pre-fabricated truss bridges that can be assembled quickly without heavy machinery, in order to help restore connectivity in Nepal.

All eyes are now on whether there will be a second wave of flash floods in the country—the possibility of which was flagged by China—that could impede the rescue efforts and also cause further damage.

In that regard, Nepali authorities are monitoring two lakes upstream of the flood ​zone, an official with ‌Nepal's Disaster Management Authority told Reuters.

Though deemed 'manageable' for rescue operations at the moment, the flood risks will remain until the two lakes have fully drained, the official added, as one of ​the two lakes began overflowing on Friday.

The other lake is said to have water pressure pent up inside, as satellite visuals showed it growing in size and bigger in surface ​area than the ​other one, but ⁠without any visible outlet as of Friday morning.

Nepalese authorities are relying on satellite ​imagery to ⁠track the status of the two lakes, though monitoring is limited, due to which it plans to install cameras ⁠and sensors ​downstream, including near the border ​town of Timure.